A compound semiconductor device is used as a field effect transistor such as a MES-FET or a HEMT (for example, see PTL 1 to PTL 6). There is a case where a device is exposed to a severe environment, and high-energy particles are incident to the device, pass through a passivation film, a source field plate, and an active region of the device and reach a substrate. At this time, a large amount of electron-hole pairs are generated around a trajectory through which the high-energy particles have passed, and are diffused or recombined according to the mobility of material, a recombination speed, and an applied voltage.